Appointment of New Director by replacing Resigned Director

Hello Everyone,

Pvt Ltd having 2 directors, in that One Director resigned on 1st April 2021 by giving resignation letter but not yet filed ROC returns and No New Director appointed till now, but willing to appoint new director as 08.10.21  for replacing Resigned director.

Please inform me that what are Companies Act compliances , and late fees will levied for non compliance.

Please also suggest how can we escape the Late fees and Non Compliance.

Resigned director ready to give new resignation letter.

Thanks in advance.